[Feature Request] Customizable user prompt character in settings.local.json

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Type: Feature Request

Title: Customizable user prompt character

Description:

Allow users to customize the input prompt character (currently >) via settings.local.json.

Use case:
When working with multiple agent profiles/projects (e.g., First agent, Second agent), it would be helpful to see which context is active directly in the prompt.

Suggested implementation:
{
"userPrompt": "[First agent] > "
}

Expected behavior:
Instead of:
> my question here

Display:
[First agent] > my question here

This would improve UX when switching between different project/topics/tickets contexts.

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